uniq man page

uniq — report or omit repeated lines

TL;DR

sort {{file}} | uniq

sort {{file}} | uniq -u

sort {{file}} | uniq -d

sort {{file}} | uniq -c

sort {{file}} | uniq -c | sort -nr

Synopsis

uniq [OPTION]... [INPUT [OUTPUT]]

Description

Filter adjacent matching lines from INPUT (or standard input), writing to OUTPUT (or standard output).

With no options, matching lines are merged to the first occurrence.

Mandatory arguments to long options are mandatory for short options too.

-c, --count
prefix lines by the number of occurrences
-d, --repeated
only print duplicate lines, one for each group
-D
print all duplicate lines
--all-repeated[=METHOD]
like -D, but allow separating groups with an empty line; METHOD={none(default),prepend,separate}
-f, --skip-fields=N
avoid comparing the first N fields
--group[=METHOD]
show all items, separating groups with an empty line; METHOD={separate(default),prepend,append,both}
-i, --ignore-case
ignore differences in case when comparing
-s, --skip-chars=N
avoid comparing the first N characters
-u, --unique
only print unique lines
-z, --zero-terminated
line delimiter is NUL, not newline
-w, --check-chars=N
compare no more than N characters in lines
--help
display this help and exit
--version
output version information and exit

A field is a run of blanks (usually spaces and/or TABs), then non-blank characters. Fields are skipped before chars.

Note: 'uniq' does not detect repeated lines unless they are adjacent. You may want to sort the input first, or use 'sort -u' without 'uniq'. Also, comparisons honor the rules specified by 'LC_COLLATE'.

Author

Written by Richard M. Stallman and David MacKenzie.

Reporting Bugs

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report uniq translation bugs to <http://translationproject.org/team/>

See Also

comm(1), join(1), sort(1)

Full documentation at: <http://www.gnu.org/software/coreutils/u…>
or available locally via: info '(coreutils) uniq invocation'

Referenced By

bmake(1), comm(1), join(1), sort(1).

November 2016 GNU coreutils 8.26 User Commands